Improving the Results of Spectroscopy in the Field

Chris Pederson, Product Line Manager at Viavi Solutions, talks to AZoM about field spectroscopy and how it has improved.

What are you presenting to visitors at Pittcon this year?

We are presenting our MicroNIR™ PAT products for process control. We are also presenting our MicroNIR™ OnSite system, which is a handheld near-infrared sensor. We have a new suite of different accessories to address, many types of application and sampling challenges to make the NIR systems more usable in various market applications.

Where do you think the major developments in handheld spectrometers for rapid material analysis has been over the past ten years?

I think it has been two-fold. Number one is that the handheld sensors continue to get smaller. At the same time the performance attributes of the sensors keep increasing. You can take applications that were previously limited to laboratory applications and start to replicate a lot of those applications more effectively, and more cost effectively, in the field or into process control applications.

The real advantage of the MicroNIR™ technology is that it is not a traditional spectrophotometer. It is more of a near-infrared sensor. No moving parts, very robust, very reliable over time. When you start removing uncertainties related to moving parts, and lots of high-end mechanical design, it lends itself well for a very robust field system. I think that is the most important attribute of sensors moving forward; simplicity, ruggedness, robustness and reliability.

What are the traditional challenges for taking process monitoring and material analysis out of the post-production laboratories and into the field?

In specific terms to near-infrared, the big challenge is sample interface. When working in a laboratory setting, you have complete control over the sample. You can perform some sample preparation, and you have control over environmental influences like temperature and humidity. That means you get precision and repeatability in your results.

When you move out into the field, you have absolutely no control of the environment. You have temperature and humidity variation which can influence the sensors. That is where it comes back into the improvements in the calibration algorithms that the systems are using, improvements in the optical design and the stability of the sensors. All those things combined help to make for a more robust measurement in the field.

The final part of it is sample interface. When you are in the lab, you have perfect control over how the sample is presented to the spectrometer. In the field, you don't always have the level of sampling. You need to get more innovative about sampling methodologies of field samples. With the MicroNIR™, we’ve created a variety of different accessories that can very easily interface with the spectrometer, and can address different sampling challenges in the field more efficiently and in an easier to use standpoint.

Outside the lab, you can't be dealing with a glass cuvette to do a liquid because you don't have the time to clean it. It's a pain. We have created attachments that you can put a couple drops of liquid on, do the measurement, then simply wipe it clean. The whole process is quick and fast. The result is after one sample you can then go on to the next sample. It does not require the level of hands-on preparation of the samples. That is what is closing that gap between process and lab into the field is just better tools for easier spectral acquisition in the field.

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Producing reproducible results for particle sizes is an important factor in a variety of industries. How does the MicroNIR™ Side View Vial Holder allow users to achieve this when measuring powders and materials with small particle sizes?

The primary benefit of the side-view vial holder is its ability to perform liquid analysis in the field. Traditionally, liquid analysis in the field is done through a cuvette, which is a pain to clean sometimes, and you do not want cross-contamination. With the side-view vial holder we have standardized on an inexpensive glass vial. You do not have to wash and reuse the same vial, or the same cuvette.

You can quickly load a liquid sample into that vial, put in the reflector mechanism and you have a very quick, very easy, reproducible liquid transflection measurement. It allows you to take a rapid quality assessment of edible oils or different types of liquid samples in the field.

How it relates to powder; the particle size and diffuse reflectants is a function of spot size. The side-view vial holder has a relatively large spot size. If you have particle size variation, looking at a larger spot size allows you to still produce good, consistent results, regardless of what the particle size is.

What does the MicroNIR™ offer for users looking to measure large particle size materials?

There are two different approaches that we are taking for large particle size analysis. Traditionally, large particles are analyzed using a sample spinner, or a rotating tray of some type. At Viavi, we have developed a very small table-top accessory that works off a standard Petri dish. You can load the sample into that and very easily do a uniformity measurement across a very heterogeneous sample.

The advantage to this device is that we have made it so that it's USB-powered. You can power it from a battery that we use to charge/recharge our cell phones. You can plug it in and use it in the field, no problem. Recognizing that it is not necessarily handheld, but very portable. We have created two different attachments that go onto the MicroNIR™ OnSite product.

The first attachment is basically a large sample plate. We call it the “Applicator”. The idea behind it is if you've got a bulk material, say in a pail or a bucket, you put the spectrometer on it, and then you physically move the spectrometer around the sample. That simulates what a sample turntable or spinner would do.

The second approach we have created is what is called a “Shaker”. The best way to think of it is like a maraca. You load a sample, shake it up, do the scan, repeat. You can very quickly assess the variability across a heterogeneous sample.

In conjunction with the Shaker, we have added several software tools that allow you to look at the standard deviation of your results. You can trend the standard deviation between the different measurements. At a certain point in time, the standard deviation can drop below a specified threshold, and you assess the heterogeneity of that sample. The combination of software tools and a couple of simple, physical sampling accessories allow for the maximum amount of reproducibility in the field.

What benefits does the MicroNIR™ Tablet Probe offer users in the pharmaceutical industry?

When dealing with pharmaceutical tablets, the challenge is that every company makes the tablet a different size, a different form factor, a different shape. That is part of each company’s branding, they create unique shapes. When you are dealing with diffuse reflectance, when you have irregular shapes like that, the light scatters differently depending upon the angle that you are looking at it. With traditional spectroscopy, you would use what is basically an integrating sphere. That would allow the light to bounce off all the tablet to homogenize the response back.

Using the Tablet Probe, in conjunction with the MicroNIR™, creates an integrating sphere effect, but instead it is a tubular reflector. So the orientation of the tablet is less critical because the light is bouncing all around the tube, resulting in a uniform and reproducible measurement.

Beyond that, Viavi has examined tablets in blister packaging. If you are concerned about moisture content or API content of tablets that have already been put into a blister pack, or even authenticity from a brand-protection standpoint, you can now place this tube over the top the blister pack, and you can get a very quick, accurate and reproducible measurement. You are not having to worry about the orientation of the tablet. Using our optics knowledge, we create uniform scatter of light based on the different sizes and shapes of tablets.

How do you plan on developing the MicroNIR™ OnSite further?

The global trend in spectroscopy is to make sensors smaller and less expensive. Some companies are even exploring methods of integrating spectrometers into mobile devices such as cell phones and so forth. One of the big advantages at Viavi is that we are a large thin film coatings company. We already supply a variety of different technologies into consumer electronics and high-volume industries.

As we move forward, we continue to leverage our expertise in optical thin-film coatings, merging existing technologies with different smaller detector technologies. The result is we can continue to develop smaller spectrometers, at a lower cost, while maintaining high performance attributes of the sensors.

What has the feedback been like at Pittcon and what do you hope to gain from attending this year?

The show this year has been quite good for us. The feedback has been very positive. We have a wide range of products for process-control applications as well as field applications. With the global trend of taking samples out of the lab and into the field, we have a variety of different sensors and accessories that very easily enable customers. When Viavi first released the MicroNIR™ five years ago, it disrupted the industry with the idea of smaller, lower-cost form factor, yet still providing good enough performance to do a lot of common applications in the marketplace.

Fast-forward five years to today, we are selling more spectrometers, and that trend has absolutely continued. I would say it has increased quite substantially.

About Chris Pederson

Chris Pederson is the Product Line Manager at Viavi Solutions in the Optical Security and Performance Products business group. He has the responsibility for strategic marketing and business development for Viavi’s MicroNIR™ family of near-infrared spectral sensors, emphasizing applications in pharmaceuticals, biomedical, food and agriculture and security applications in brand protection and law enforcement. The Optical Security and Performance Products group provides precision optical products incorporating thin film technology for a broad array of applications and industries including defense/aerospace, instrumentation, automotive and consumer electronics.

Chris has over 16 years of experience in all aspects of sales and marketing and product management. Prior to joining Viavi in 2012, he worked for Analytical Spectral Devices Inc. (ASD) and DeltaNu Inc. in various sales, marketing and product management capacities. Chris holds Bachelors of Science degrees in Chemistry and Biology from Northern State University and his MBA from Regis University.